ECM is opposite of electrochemical or galvanic coating or deposition process.

ECM can be thought of a controlled anodic dissolution at atomic level of the work piece.

It is electrically conductive by a shaped tool due to flow of high current at relatively low potential difference. An electrolyte, which is quite often water based neutral salt solution is used as a medium.

ECM is often characterized as reverse electroplating.

This process is similar in concept to electrical discharge machining in that a high current is passed between an electrode and the part, through an electrolyte.

The material removal process having a negatively charged electrode (cathode), a conductive fluid (electrolyte) and a conductive work piece (anode);

Schematically shows the basic principle of ECM

During ECM, there will be reactions occurring at the electrodes i.e. at the anode or work piece and at the cathode or the tool along with within the electrolyte.

As the potential difference is applied between the work piece (anode) and the tool (cathode), the positive ions move towards the tool and negative ions move towards the workpiece.

Thus the hydrogen ions will take away electrons from the cathode (tool) and from hydrogen gas as:

2H+ + 2e- = H2↑ at cathode

Similarly, the iron atoms will come out of the anode (work piece) as:

Fe = Fe+ + + 2e-

Within the electrolyte iron ions would combine with chloride ions to form iron chloride and similarly sodium ions would combine with hydroxyl ions to form sodium hydroxide

Na+ + OH- = NaOH

Schematic representation of electro-chemical reactions

Schematic diagram of an electrochemical drilling unit

No tool wear as non contact working mode avoiding problems such as vibration and breakage.

High material removal rate.

Ability to machine a wide variety of materials without affecting microstructure or surface properties.

No heat generated during machining.

Cutting, drilling, deburring and shaping possible.

Environmentally acceptable.

Difficulty in learning to use the process

Heavy initial investment

Difficulty in designing a proper tooling system

Process Parameters